code: def test_str_cat_result_is_a_string_and_new_column_names(no_nulls_df):
      """
      Test wrapper for Pandas `.str.cat()` method when the outcome is a string,
      and `new_column_names` is not None.
      """
  
      result = no_nulls_df.process_text(
          column_name="text",
          string_function="cat",
          new_column_names="combined",
      )
  
      expected = no_nulls_df.assign(
          combined=no_nulls_df["text"].str.cat()
      )
  
      assert_frame_equal(result, expected)
  
imports: import numpy
  import pandas
  import pytest
  from pandas.testing import assert_frame_equal
label_desc: Use image node_id 15 for calling a global function with example usage: test_str_cat_result_is_a_string_and_new_column_names(no_nulls_df) without return types